The secret to getting the best deal is to know your prices (and to quickly do the math to see which is better. If you can't do then math in your head, then google search the answer (It acts like a calculator), get a free calculator, or buy a calculator. I saw super nice TI non - graphing calculators for $9.99 at Office Depot, so don't pay more than that. I believe you can get basic calculators at most dollar stores for $1.)
For example, last weekend, I went to Moody Gardens. The lowest hotel price was $2.29 + tax. Plus, we wanted the unlimited passes, which were advertised at $49. They were (and still are) doing a promotion of Buy 1 day, get a second day free on the unlimited passes. Btw, you save at least $30 by doing the unlimited pass bundle if you actually do everything. These passes go for a few dollars less if you buy them online. They also offer at the park that you can upgrade the day pass to a summer pass for $35 dollars.
Moody Gardens offered us a package deal. Get a nice room plus 2 tickets and free valet parking for $289, including tax. Now do the math. It is like getting one of those tickets for free at least. So, this is an example where bundles are good!
Second example, Kids meals at most fast food places. McDs offers their hamburger kids meal for $2.49. A small fries, and small drink come off the dollar menu at $1/item. That leaves you $0.50 for a hamburger and a toy. Deal!
Same thing with the Chick Fil A Kids Meal. Check it out.
Next example, today I went to La Madeline to try their new tea (for free!), and I got the duet magnifique. I had half a cold sandwich (tuna), a small side cesear salad, and a bowl of tomato soup (add $1.20 for a bowl instead of cup). for $6.99 + $1.20 + free drink + tax. My little one and I shared saving us the $4.19 on the kids meal, which he probably wouldn't have eaten. If I remember correctly, the bowl of soup would have been around $5 by itself and the side salad about $4. Woohoo! ps. We love to dip their bread into the soup. Yum!
Bundles only work if you want everything in the bundle. If you don't, then it might be cheaper to go a la carte than to buy things you don't need and cant use.
A la carte is often better at sit down restaurants.
I know many mexican restaurants often make bundle meals (and it is like getting the rice and/or beans for free), but what if you don't want the rice or beans or just want a stuffed avocado. or you want 1 stuffed avocado and 1 chile relleno. Then, look at the a la carte menu. You can find some real deals, and make your own meal. Casa Imperial comes to my mind on this topic.
Sometimes restaurants charge you for silly things so check the prices before you order or be brave and ask your server how much something costs.
Most Mexican restaurants will bring you tortillas for free, but some charge.
This reminds me of my internal debate of whether or not it is worthwhile to get a kids meal. Some kids meals aren't anything special and are overpriced. Others are great and are generous. This is where ordering something a la carte to add to your meal can be a fab idea. Sometimes, we get an appetizer and a main course and share, too. (think queso! mmm)
Some places market things as bundles and you don't save any more than if you buy them separately or they even charge more then if you order off of the a la carte menu.
So, overall it doesn't matter which way you order as long as you are getting what you want and you do different combinations in your head to see how the price comes out best.